1. Field of the Invention
The present invention relates to the detection of materials, and in particular to an apparatus and method that detects the presence of a given material in any location using a characteristic frequency of the material.
2. Scope of the Prior Art
The ability to detect the presence of a material in any location is a requirement in many disciplines and industries. Determining if a particular material in large or small quantities is present at any location is a concern in medicine, research, exploration forensics, security, law enforcement, and for safety reasons. For example, at points of entry for national borders, and at some complexes, and buildings it can be necessary that contents of baggage and boxes and other such cargo containers be identifiable by inspection or detection methods when searching for contraband such as narcotics, stolen goods, unauthorized medicines and plants explosives and accelerants, liquids, chemicals, and other materials. There are similar requirements for unobtrusively searching people, as well as for searching of modes of transportation such as motor vehicles, aircraft and vessels for contraband cargo including the presence of hidden human cargo. Detection technology is applicable in medicine for detection of toxins, broken bones, tumors, and foreign objects introduced to the body. Forensic science and other fields of research also use detection technology for both verification and exploratory reasons.
To detect objects, materials and things that are not detectable by the human eye for any given reason, many different types of devices and methods have been developed. One of the most common is X-ray technology. X-ray devices are used to inspect luggage, baggage and other containers. While X-ray technology works well in some cases by identifying the shape of objects within a container, it lacks in the ability to detect some materials or to penetrate some container materials.
X-ray technology is also used in the field of medicine to observe the internal structure of the human or animal body. Similarly, Magnetic Resonance Imagining (MRI) technology and Nuclear Magnetic Resonance (NMR) technology is employed in medicine and other fields with advantages to each. CAT scans, which uses NMR technology, and MRIs are considered by some to be safer when used on humans than X-ray technology. But as with X-ray technology, these machines employing these other technologies are expensive, and cannot detect all materials in all locations. NMR has been used to detect contraband material. In order to be effective in detecting materials, NMR requires relatively large magnets which are expensive. Another limitation of NMR is that it can expose humans to strong magnetic fields. One draw back to NMR is that its magnets can damage magnetically stored information commonly found in computers.
Nuclear Quadrupole Resonance (NQR) is another method of detecting material. NQR is similar to NMR but doesn""t require the use of large magnets. It uses a range of radio frequency spectroscopy that exploits the inherent electrical properties of atomic nuclei. Accordingly, an atomic nucleus emits a quadrupole resonance when the nucleus encounters a specific given electrical field that is produced by a surrounding environment. Typically, when exposed to a given frequency, a material responds and emits an NQR signal. Each given material has a set of given NQR frequencies that are dependent on the chemical structure of the material. For example, nitrogen (14N) is a chemical structure found in some narcotics and explosives. When the appropriate radio frequency for nitrogen (14N) is exposed to an explosive or narcotic containing nitrogen (14N), the material will emit an NQR signal.
Different types of devices have been developed to use the NQR of nitrogen (14N) to detect the presence of explosives particularly in airline luggage and other a transportation containers. In order to be effective, most devices that operate on NQR use equipment that can both transmit and receive radio frequencies. Those devices also require relatively high energy sources to effectively create an NQR signal that can be detected from the material. Even with high energy sources, the NQR signal emitted from the material has a low energy that is relatively hard to detect. For example, an NQR detection device that has a 2 kW source can detect the presence of a given material from only centimeters away. Thus, the transmitter and receiver must be relatively close to the substance to actually detect its presence. Because of the relatively low energy emitted by the substance, NQR detection devices can effectively only detect the presence of explosives or other materials in a given location. Accordingly, suitcases and the like must be placed in a relatively small space in order for NQR to be used to detect the presence of contraband.
In addition to NMR and NQR materials have other types of spectral fingerprints. These spectral fingerprints depend on the chemical components that make up the material. When a given material is exposed to an energy signal of a given frequency that corresponds to one of spectral fingerprints, a so-called characteristic frequency, the material will emit a corresponding energy signal having essentially the same frequency. As is the case with fluorescence, the frequency of the mirror energy emitted from a material may vary slightly from the original frequency. Most known research into these characteristic frequencies have been conducted with energy sources having a frequency of less then 10 MHz, which is the range of frequencies that a material will experience NQR.
NQR effects the atomic nuclei with respect to the electrons shielding the particular nuclei being measured. But when atoms are exposed to other energy levels, the energy causes reactions, to the electrons. The electron energy in a molecule is 1-100 electron volts (eV). This energy is also represented in parts per eV; for example, the xe2x80x9cvibration energyxe2x80x9d of an electron is measured in tenths of an electron volt, and the xe2x80x9crotation energyxe2x80x9d of an electron is measured in thousandths of an electron volt. In NQR, the nuclei can change levels when the nuclei comes in contact with an external energy source. It is believed, however, that exposure to low energy sources has an effect on the energy of the electrons. It is also believed that low level energy effects the electron orbitals.
In view of the foregoing, the present invention relates to an apparatus and method of detecting the presence of materials. It is an object of the present invention to overcome the deficiencies of the prior art. Thus, it is an object of the present invention to be able to detect a given material in an undisclosed place as well as the ability to detect a material in a given location. It is also an object of the present invention to detect the presence of a material using energy produced by an atom when it is exposed to characteristic frequencies of that given material. In addition, the apparatus should be able detect materials over a wide range with a relatively low level power source.
In order to detect the presence of a given material at any great distance, the present invention detects the interference generated between the a source energy and the characteristic energy emitted from the material. The interference signal generated between the source energy and the energy emitted from a material is a series of pulses that occur when the two signals cross. The two signals will undoubtedly be out of phase with each other. Since the two signal will be at the same general frequency, however, the interference signal will also be at that frequency. Since the characteristic energy emitted from the target material is a derivative of the characterstic energy, the interference occurs at given intervals. Even though the energy level of the signal emitted by the target material is relatively low, and can be hard to detect on its own, the interference signal is constant and does not depend upon the energy level if the signal emitted by the target source. The interference signal is constant over a wide range and can be detected because of the known parameters of the source signal and the signal emitted by the source.
Accordingly, the present invention includes a source module and a detection module. The source module generates an energy signal having a given frequency and that corresponds to the a characteristic frequency of the material to be detected. The detection module detects the presence of the interference signal that is created between the source energy signal and the energy emitted from the target material at the same frequency as the source signal. The interference signal is dependent upon the characteristic frequency of the target material.
The source module includes a frequency generator that is connected to an antenna that has a given size, or length, that depends upon the wavelength of the energy signal. The source module may also include an inductor so that a multi-phase signal will be emitted.
The detection module includes a rotatable antenna. To improve performance, the antenna can be connected to a signal generator that is preferably set to the characteristic frequency. It is believed that the generator connected to the detection module serves as an amplifier of the interference signal and a filter for surrounding frequencies. The detection module antenna is also connected to a coil that can be tightly wound and oriented in a vertical direction relative to ground and perpendicular to the antenna. The detection module can include a modulator that is set to a relatively small frequency as compared to the source signal. The modulator enhances the detection of the interference signal by the antenna by varying the interference field. The size and orientation of the antennas, the modulator and the detection module source generator are all configured to enhance the ability of the detection module to detect the presence of a material in any given location. It has been observed that the detection device of the present invention operates optimally when the source generator emits an energy signal of between 100 MHz and 1.5 GHz.
In operation, the source generator is activated to emit an energy signal of a target material""s characteristic frequency between 100 MHz and 1.5 GHz. Depending on the power level of the energy source, the source module will begin to activate the electrons of any material that has the characteristic frequency generated within a given area after a few seconds. Once the target material is activated, it too will begin to emit a signal having the characteristic frequency. As will be understood by one skilled in the art, an interference signal at the characteristic frequency will occur between the source signal and the target material signal even though the energy level of the target material signal may be relatively weak.
The detection module is moved through a range between the source module and the target material. When the detection module encounters the highest energy line between the source module and target material, which is the shortest line between the two energy sources, the antenna will rotate to designate that the line has been crossed. Depending on the orientation that the detection module coil is wound, the antenna will rotate in the direction of the target material or the source. As the antenna continues to move through a range it will continue to point in the direction of the source module and the target material. Once a set of co-ordinates for the target material have been generated then the exact location of the target can be calculated. If the exact location of the material is known, as in a suitcase, the principles of the present invention can be use to detect if a target material is in that location. The mere detection of the interference signal will indicate that location contains the target material.